THE DETECTION OF MORDANTS BY ENERGY DISPERSIVE X-RAY SPECTROMETRY
N. Indictor, R.J. Koestler, & R. Sheryll
IN A PREVIOUS STUDY A GROUP of modern mordanted textile samples was subjected to SEM-EDS analyses to determine the feasibility of identifying mordants on museum textiles.1 Successful qualitative identification was achieved on silk, cotton, and wool for samples containing the elements aluminum, iron, copper, tin and chromium. Some problems that appeared in that study were the following: significant elements are present very nearly at the limits of detectability of our analytical system; iron sometimes appeared as a trace element even when not used as a mordant; and some analyses of samples mordanted with chromium gave no indication of chromium; the same was true for tin but less frequently. Aside from the difficulties in obtaining unambiguous analyses for some samples, anticipated difficulties for museum and archaeological samples are foreseeable owing to loss of mordant during dyeing, washing, wear and aging that is certain to attend all historical samples. The presence of metallic elements from dust, dirt, soil, stains, treatment, etc., may also constitute a source of metallic elements that is not associated with the mordanting process requiring a cleaning or washing of the samples prior to analysis. Finally, not all mordants contain metallic elements2 and the mordants free of metallic elements or elements lighter than sodium would not be detected by EDS.
In the series of analyses described in this study, wool samples were mordanted and dyed with cochineal3 and submitted without identification for SEM-EDS analysis. For each sample analyzed, metallic elements of the mordants actually used were identified unambiguously. The quantity of metallic element present in the mordanted samples, as determined by atomic absorption (AA), was also obtained. SEM photomicrographs of the samples were taken and examined for indications of the effects that mordants and/or additives had on the surface structure.